Microelectronic device manufacturing in coordinated carbon dioxide processing chambers

ABSTRACT

A system for processing microelectronic substrates in a liquid or supercritical carbon dioxide process media comprises (a) a plurality of carbon dioxide processing chambers; (b) a carbon dioxide supply vessel operatively associated with each of the carbon dioxide processing chambers; (c) a first process chemical supply vessel operatively associated with at least one of the carbon dioxide processing chambers; (d) a waste collection vessel operatively associated with at least one of the carbon dioxide processing chambers; and (e) a controller operatively associated with the plurality of processing chambers, the carbon dioxide supply vessel, the vacuum pump if present, the first process chemical supply vessel, and the waste collection vessel, the controller configured to independently process microelectronic substrates in each of the processing chambers.

FIELD OF THE INVENTION

[0001] The present invention concerns methods of manufacturingmicroelectronic devices, and particularly concerns methods ofmanufacturing microelectronic devices in a plurality of integrated orcooperating carbon dioxide processing chambers.

BACKGROUND OF THE INVENTION

[0002] Production of integrated circuits, microelectronic devices, andmicro-electo mechanical devices, (MEM's) involve multiple processingsteps many of which incorporate water as either a carrier of chemistry,or a media to facilitate the removal of process byproducts. Theevolution of materials and processes has been lead by a drive towardsmaller feature sizes and more complex microdevices. In some cases, theuse of water in these evolving processes has resulted in challengeswhereby deleterious effects of water and byproducts carried by waterhave been seen. The unique physical properties of dense carbon dioxidein a liquid or supercritical state are of particular interest inpreventing certain of these pitfalls.

[0003] Methods for the cleaning of microelectronic devices with carbondioxide are described in U.S. Pat. No. 5,783,082 to DeSimone et al.

[0004] Methods for the spin-coating and spin cleaning of microelectronicdevices are described in U.S. Pat. No. 6,001,418 to DeSimone andCarbonell.

[0005] Methods for the coating of substrate with a carbon dioxidesolvent system are set forth in, among others, U.S. Pat. No. 6,165,559to McClain et al.

[0006] Methods for the chemical mechanical planarization ofmicroelectronic devices with carbon dioxide are set forth in PCTApplication WO 02/38335 (16 May 2002) to McClain and DeSimone.

[0007] To obtain the maximum benefit from various carbon-dioxideprocessing steps, there remains a need for microelectronic processingsystems and methods which provide a coordinated processing of devices orsubstrates in a plurality of different carbon dioxide processingchambers.

SUMMARY OF THE INVENTION

[0008] The present invention provides systems and methods in which aplurality of different carbon dioxide processing chambers arecoordinated through a common controller in the processing ofmicroelectronic devices or substrates. In some embodiments, the amountof waste material generated by non-carbon dioxide processing steps isadvantageously reduced. In some embodiments, the processing timerequired to manufacture the devices is advantageously reduced.

[0009] A first aspect of the present invention is, accordingly, a systemfor processing microelectronic substrates in a liquid or supercriticalcarbon dioxide process media, comprising:

[0010] (a) at least one, and preferably a plurality of (e.g., at leasttwo or three) carbon dioxide processing chambers;

[0011] (b) a carbon dioxide supply vessel operatively associated witheach of the carbon dioxide processing chambers;

[0012] (c) optionally but preferably a vacuum pump operativelyassociated with at least one of, or each of, the carbon dioxideprocessing chambers;

[0013] (d) a first process chemical supply vessel operatively associatedwith at least one of the carbon dioxide processing chambers;

[0014] (e) a waste collection vessel operatively associated with atleast one of the carbon dioxide processing chambers; and

[0015] (f) a controller operatively associated with the plurality ofprocessing chambers, the carbon dioxide supply vessel, the vacuum pumpif present, the first process chemical supply vessel, and the wastecollection vessel, the controller configured to independently processmicroelectronic substrates in each of the processing chambers.

[0016] In another respect, the present invention provides a system forprocessing microelectronic substrates in a liquid or supercriticalcarbon dioxide process media, comprising:

[0017] (a) a transfer module;

[0018] (b) a plurality of processing chambers, said plurality includingat least one, and preferably a plurality (e.g., at least two or three)of carbon dioxide processing chambers, operatively associated with thetransfer module so that microelectronic substrates in one of theplurality of processing chambers may be processed therein and thentransferred to another of the plurality of processing chambers throughthe transfer module for further processing therein;

[0019] (c) a carbon dioxide supply vessel operatively associated witheach of the carbon dioxide processing chambers;

[0020] (d) optionally but preferably a vacuum pump operativelyassociated with at least one of, or each, of the carbon dioxideprocessing chambers;

[0021] (e) a first process chemical supply vessel operatively associatedwith at least one of the carbon dioxide processing chambers;

[0022] (f) a waste collection vessel operatively associated with atleast one of the carbon dioxide processing chambers; and

[0023] (g) a controller operatively associated with the transfer module,the plurality of processing chambers, the carbon dioxide supply vessel,the vacuum pump if present, the first process chemical supply vessel,and the waste collection vessel, the controller configured toindependently process microelectronic substrates in each of the carbondioxide processing chambers.

[0024] The foregoing and other objects and aspects of the presentinvention are explained in greater detail in the drawings herein and thespecification set forth below.

BRIEF DESCRIPTION OF THE DRAWING

[0025]FIG. 1 is an illustrative embodiment of a system of the presentinvention in which a cluster tool is used as the transfer module.

[0026]FIG. 2 is a schematic diagram of a second embodiment of thepresent invention.

[0027]FIG. 3 is a flow chart illustrating an example process which maybe carried out with an apparatus of the invention, and the sequence ofchambers used to carry out that process.

[0028]FIG. 4 is a flow chart illustrating one embodiment of thephotoresist etch step of FIG. 3.

[0029]FIG. 5 is a flow chart illustrating another embodiment of thephotoresist etch step of FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The present invention is explained in greater detail below. Thisdescription is not intended to be a detailed catalog of all thedifferent ways in which the invention may be implemented, or all thefeatures that may be added to the instant invention. For example,features illustrated with respect to one embodiment may be incorporatedinto other embodiments, and features illustrated with respect to aparticular embodiment may be deleted from that embodiment. In addition,numerous variations and additions to the various embodiments suggestedherein will be apparent to those skilled in the art in light of theinstant disclosure which do not depart from the instant invention.Hence, the following specification is intended to illustrate someparticular embodiments of the invention, and not to exhaustively specifyall permutations, combinations and variations thereof.

[0031] As used herein, the term “microelectronic substrate” should beinterpreted broadly to include semiconductor substrates, semiconductorsubstrates on which one or more layer resides, integrated circuits,microelectronic workpieces, microelectronic devices, compoundsemiconductors, memory devices such as thin-film read-write heads,MEM's, MEOM's and opto-electronic devices.

[0032] A “carbon dioxide processing chamber” as used herein refers to aprocessing chamber for microelectronic devices which contains orincludes a sealing assembly so that liquid, or supercritical carbondioxide may be contained therein to participate in the processing of amicroelectronic device or substrate therein. A carbon dioxide processingchamber will be operatively associated with a carbon dioxide source orsupply.

[0033] A “non-carbon dioxide processing chamber” as used herein refersto a processing chamber for microelectronic devices which is notoperatively associated with a carbon dioxide source or supply (e.g., bythe nature of the processing chamber operating under low-pressure gas,vacuum or alternative liquid, or by cutting off such a supply through avalve or pipe reconfiguration when a particular process does not requirecarbon dioxide processing within that particular chamber). Such achamber may contain other solvent systems, such as aqueous or organicsolvents, or may be used to carry out other processes such asirradiation or metrology.

[0034] A “transfer module” as used herein may be any suitable transfermodule or apparatus, including a single robot, a pod of robots, etc. Thetransfer module may be in any suitable geometry, including stackedtransfer modules, track transfer modules, cluster transfer modules, etc.

[0035] As used herein, the term “processing time” means the time elapsedduring a given process. For a process module, the process time ismeasured from the time a microelectronic substrate completely crossesthe threshold of the process module (e.g., the module's pressurechamber) when placed into the module until the time the microelectronicsubstrate completely crosses the threshold of the process module whenremoved from the module.

[0036] A first embodiment of the apparatus of the invention is given inFIG. 1. The apparatus comprises a transfer module 11 and a plurality ofassociated processing chambers 12, 13. Two such chambers are shown forsimplicity, but many more could be included. As illustrated, bothchambers are carbon dioxide processing chambers, but non-carbon dioxideprocessing chambers may be included within the system as desired. Notethat while a vacuum pump 25 is illustrated as the preferred embodiment,those skilled in the art will appreciate that the vacuum pump is notessential, and if necessary alternatives to the vacuum pump may beprovided.

[0037] Chambers 12, 13 may for example be spin coating and/or spincleaning chambers, such as described in U.S. Pat. No. 6,001,48 toDeSimone and Carbonell. (the disclosure of this and all other UnitedStates patents cited herein are to be incorporated by reference hereinin their entirety).

[0038] Associated with the transfer module 11 and chambers 12, 13 isbulk carbon dioxide supply 21, carbon dioxide supply 22, first processchemical supply 23, second process chemical supply 24, vacuum pump 25,waste collection system 26, and controller 31.

[0039] Carbon dioxide may be delivered to the system in any form. In apreferred embodiment, the carbon dioxide is delivered to bulk storagetank 21 located on site at the processing plant, which storage tankcontains the carbon dioxide as a cryogenic liquid (saturated liquid,pressure less than 350 psig, temperature preferably from −10 to 10° F.).This facilitates delivery of carbon dioxide solvent from existingdistributors, such as those in place for the beverage industry. Carbondioxide from the bulk storage supply may then be transferred by pumpinginto carbon dioxide supply system 22, which may comprise a workingvessel in which the carbon dioxide is maintained at a desired pressureand temperature, and optionally includes other ingredients added to thesystem, for use in the processing system, and optionally includesprocess capabilities such as distillation, filtration, absorption andmembrane separation to purify the CO₂.

[0040] Process chemical supply systems 23, 24 are illustrated asseparate from the carbon dioxide supply system 22, but in practice thesetwo systems may be interrelated, depending upon how process chemicalsare to be combined with carbon dioxide (if they are to be so combined).For example, process chemicals can be added to the carbon dioxide underlow pressure, for example in a carrier solution or co-solvent, or addedto the carbon dioxide under high pressure, for example by injection intoa carbon dioxide supply line under conditions that impart turbulentflow, etc. Examples of suitable techniques for adding chemicals to thecarbon dioxide include but are not limited to those given in U.S. Pat.No. 6,148,645 to DeYoung et al. (the disclosures of all patentreferences cited herein are to be incorporated herein by reference intheir entirety).

[0041] When used as a carrier for a compound to be distributed anddeposited on the top surface portion of the substrate, the carbondioxide liquid is a mixture that contains carbon dioxide, optionally oneor more cosolvents, and one or more compounds to be carried. Exemplarycompounds that may be carried by the carbon dioxide liquid include, butare not limited to, polymers (including polymer precursors or monomersthat polymerize or are polymerized after deposition), resists (e.g.,photoresists, electron resists, x-ray resists), adhesion promoters,antireflective coatings, sol-gel precursors, metals and metal layerprecursors, and CMP chemical components. Resists such as photoresistsmay also contain additives to improve lithographic performance includingdissolution inhibitors, photo acid generators, and the like. The photoacid generators are present to allow for chemically amplified resisttechnology. The mixture may be in any physical form, includingsolutions, dispersions, and emulsions, but preferably the mixture ishomogeneously distributed, more preferably a solution. In a preferredembodiment, the mixture is comprised of carbon dioxide and afluoropolymer, and more preferably a fluoroacrylate polymer. Examples ofsuch mixtures are disclosed as the polymerization product described inU.S. Pat. No. 5,496,901 to DeSimone, the disclosure of which isincorporated herein by reference. In a preferred embodiment, suchmixtures are applied to the top surface portion of a semiconductor(e.g., silicon) substrate substrate to serve as a photoresist.

[0042] The carbon dioxide liquid may contain a viscosity modifier suchas an associative polymer to increase the viscosity thereof and alterthe thicknesss of the surface coating. The viscosity modifier may, forexample, be included in an amount sufficient to increase the viscosityof the carbon dioxide liquid up to about 1, 10 or 100 centipoise.

[0043] The carbon dioxide liquid may contain a surface tension modifier(e.g., a surfactant) to increase or decrease the surface tension by anamount up to about plus or minus 5 dynes per centimeter. Surface tensionmodifiers may be included to increase or decrease droplet formation atthe boundary of the carbon dioxide liquid coating formed on thesubstrate during spinning thereof. Surfactants used as such surfacetension modifiers should include a CO.sub.2-philic group and aCO.sub.2-phobic group and are known in the art. See, e.g., U.S. Pat. No.5,312,882 to DeSimone et al.; U.S. Pat. No. 5,683,977 to Jureller et al.(the disclosures of which are incorporated by reference herein in theirentirety).

[0044] If desired, the carbon dioxide liquid may contain a co-solventthat evaporates more slowly than does carbon dioxide (e.g., alcohols,ketones such as cyclopentanone, butyl acetate, xylene). Substratescoated with such a carbon dioxide liquid may then be removed from thepressure vessel and dryed (e.g., in a separate drying oven, as describedin U.S. Pat. No. 4,794,021 to Potter). Such a technique may be employedto reduce pin holes in the coating formed on the substrate.

[0045] Carbon dioxide compositions may be added to processing chambersand/or applied to the substrate in any suitable form and by any suitabletechnique such as dipping, roller coating, doctor blading, spin coating,spraying, etc., but are preferably provided as a dense phase carbondioxide (i.e., liquid or supercritical fluid). It may be desired tomaintain an essentially constant atmosphere within a chamber as carbondioxide liquid is applied during one (or more) application steps. Inthis case, an atmosphere of carbon dioxide and one or more additionalgasses or inert gasses (e.g., helium, nitrogen, argon, oxygen) can bepassed into and out off the chamber above in a controlled manner, sothat the composition of the atmosphere within the chamber remainsconsistent as material is added to the chamber.

[0046] A vacuum pump 25 is provided to evacuate carbon dioxide chambersprior to the addition of carbon dioxide thereto. Other suitable controlelements such as compressors, condensers, liquid pumps, storage vesselssuch as liquid, fluid, or vapor storage vessels, supply vessels such asliquid, fluid or gas supply vessels and the like may be included in thesystem in any of a variety of configurations to facilitate the movementof gases, liquids and supercritical fluids within the system, asdescribed in U.S. Pat. No. 6,332,342 to McClain et al. In an alternativeembodiment the chamber can be flushed with carbon dioxide from 22 or 21to remove ambient air in the chamber prior to addition of the carbondioxide composition. In still another embodiment one may forego controlof air by the vacuum pump, unless one is recycling the carbon dioxidefor subsequent use in the process and it is desired to avoidcontamination of the carbon dioxide with other gases found in air.

[0047] Any suitable controller or control system 31 may be used to carryout the present invention. In FIG. 1, lines from the controller 31 tothe remaining apparatus are not shown for the sake of clarity, but maybe implemented as electrical, mechanical, pneumatic, or any othersuitable control mechanism or device. A programmable logic controllermay serves as a control means to provide the valve configurations neededto achieve the cycles described below. On example is an Allen BradleySLC500 programmable logic controller (PLC), which is programmed usingthe A/B programming language in accordance with known techniques. Theparticular control means used is not critical, and can be implementedwith a any of a variety of different hardware, software, and combinationhardware/software systems, including a variety of different computers,interface boards, or program languages, numerous of which are known topersons skilled in the art.

[0048] The system includes a waste collection system 26, which mayinclude a purifier (e.g., a still, adsorption, sublimation, single ormulti-stage distillation, or other such purifying apparatus orcombination thereof) and associated vessels for purifying contaminatedcarbon dioxide liquid to provide carbon dioxide (which may be returnedto the carbon dioxide supply 22 for re-use) and purified waste, whichpurified waste may be collected and removed from the system forsubsequent disposal. The system may advantageously provide forcoordinated waste removal from processes carried out in a variety ofchambers.

[0049] The transfer module and associated chambers may be located withina clean room on one side of line 32-32, the bulk carbon dioxide supply21 may be located exterior or separate from other system componentsoutside line 33-33, and some or all of the remaining system components23, 24, 25, 26, 31 located in a common support room or area outside ofthe clean room in which transfer modules 11, and chambers 12, 13 arelocated.

[0050] As illustrated in FIG. 2, a system of the present invention maybe implemented with a plurality of processing stations 41, 42, 43located within a clean room, all of which are supported by common carbondioxide, chemical supply, optional vacuum supply, and control, and wastecollection outside of that clean room, along with bulk carbon dioxidelocated elsewhere (preferably in near proximity, within about 300 feet,and preferably outside the building in which the remainder of the systemis housed). Each processing chamber comprises a transfer module and aplurality of associated chambers as described above, with at least one,and preferably at least two, of the chambers on each processing chamberbeing carbon dioxide processing chambers.

[0051]FIG. 3 illustrates one example of a process that may be carriedout with the instant invention. The process involves the step ofdepositing a photoresist 51 in a first chamber, which is preferably acarbon dioxide chamber such as a spin coating chamber as describedabove. The next step is a photoresist exposure step 52, which is carriedout in a chamber in which the photoresist is exposed to radiant energysuch as light (e.g., ultraviolet light) to develop the photoresist, inconjunction with a suitable mask in accordance with known techniques(note that photoresist exposure is preferably not a carbon dioxideprocessing step). The next step involves developing the photoresist 53,which may be carried out in a carbon dioxide chamber by contacting theexposed substrate to an appropriate development solution, such as carbondioxide as described in US Patent Application 2002/0119398 to DeSimoneet al. The final step or set of steps may involve etching of thesubstrate 54 to remove undesired oxide layers from bare silicon and/ormetal. The etch step may be carried out as shown in FIG. 4 by firstashing the photoresist by plasma etching, heating in an oven or the likein chamber 54 a and then cleaning the ashed photoresist in a cleaningchamber 54 b. In another embodiment, the etch step may be carried out asshown in FIG. 5 by first stripping the photoresist in a chamber 54 e(e.g., with suitable chemical treatments which may be carried by carbondioxide) and then cleaning the substrate in cleaning step 54 f (whichmay optionally be the same chamber in which the stripping step 54 e iscarried out). Cleaning chambers 54 b, 54 f may be carbon dioxidecleaning chambers, and may involve the use of a carbon dioxide liquidcontaining surfactants, co-solvents or other cleaning adjuncts, and/ormay utilize a final cleaning step with pure carbon dioxide.

[0052] The foregoing is illustrative of the present invention, and isnot to be construed as limiting thereof. The invention is defined by thefollowing claims, with equivalents of the claims to be included therein.

That which is claimed is:
 1. A system for processing microelectronicsubstrates in a liquid or supercritical carbon dioxide process media,comprising: (a) at least one carbon dioxide processing chamber; (b) acarbon dioxide supply vessel operatively associated with each of saidcarbon dioxide processing chambers; (c) a first process chemical supplyvessel operatively associated with at least one of said carbon dioxideprocessing chambers; (d) a waste collection vessel operativelyassociated with at least one of said carbon dioxide processing chambers;and (e) a controller operatively associated with said plurality ofprocessing chambers, said carbon dioxide supply vessel, said firstprocess chemical supply vessel, and said waste collection vessel, saidcontroller configured to independently process microelectronicsubstrates in each of said processing chambers.
 2. A system according toclaim 1, further comprising a storage vessel operatively associated withsaid controller and each of said carbon dioxide processing chambers. 3.A system according to claim 1, further comprising a second processchemical supply vessel operatively associated with said controller andat least one of said carbon dioxide processing chambers.
 4. A systemaccording to claim 1, further comprising a supply vessel operativelyassociated with said controller and at least one of said carbon dioxideprocessing chambers.
 5. A system according to claim 1, wherein said atleast one carbon dioxide processing chambers comprises at least twoseparate processing chambers.
 6. A system according to claim 1, furthercomprising a bulk carbon dioxide storage vessel operatively associatedwith said carbon dioxide supply vessel.
 7. A system according to claim1, further comprising: an abatement chemical supply vessel operativelyassociated with said waste collection vessel for adding detoxificationor neutralization chemicals to the contents of said waste collectionvessel.
 8. A system according to claim 1, further comprising: a purifieroperatively associated with said waste collection vessel for separatingcarbon dioxide from waste chemicals.
 9. A system according to claim 8,further comprising: a return line connecting said purifier to saidcarbon dioxide supply vessel for returning said carbon dioxide from saidpurifier to said carbon dioxide supply vessel.
 10. A system according toclaim 8, further comprising: an abatement chemical supply vesseloperatively associated with said purifier for adding detoxification orneutralization chemicals to said waste chemicals.
 11. A system accordingto claim 1, further comprising: a clean room containing said pluralityof carbon dioxide processing chambers; and a control room containingsaid carbon dioxide supply vessel, said vacuum apparatus, and said firstprocess chemical supply vessel.
 12. A system according to claim 11, saidcontrol room further containing said controller and said wastecollection vessel.
 13. A system according to claim 11, furthercomprising a bulk carbon dioxide storage vessel operatively associatedwith said carbon dioxide supply vessel, with said bulk carbon dioxidestorage vessel positioned outside said control room.
 14. A systemaccording to claim 1, further comprising at least one non-carbon dioxideprocessing chamber operatively associated with said controller.
 15. Asystem according to claim 1, further comprising a vacuum pumpoperatively associated with at least one of said carbon dioxideprocessing chambers and said controller.
 16. A system for processingmicroelectronic substrates in a liquid or supercritical carbon dioxideprocess media, comprising: (a) a transfer module; (b) a plurality ofprocessing chamber including at least one carbon dioxide processingchamber operatively associated with said transfer module so thatmicroelectronic substrates in one of said plurality of processingchambers may be processed therein and then transferred to another ofsaid plurality of processing chambers through said transfer module forfurther processing therein; (c) a carbon dioxide supply vesseloperatively associated with each of said carbon dioxide processingchambers; (d) a first process chemical supply vessel operativelyassociated with at least one of said carbon dioxide processing chambers;(e) a waste collection vessel operatively associated with at least oneof said carbon dioxide processing chambers; and (f) a controlleroperatively associated with said transfer module, said plurality ofprocessing chambers, said carbon dioxide supply vessel, said vacuumapparatus, said first process chemical supply vessel, and said wastecollection vessel, said controller configured to independently processmicroelectronic substrates in each of said processing chambers.
 17. Asystem according to claim 16, comprising, in operative association withsaid transfer module, and sequentially operatively associated with oneanother: a carbon dioxide photoresist deposition chamber; a photoresistexposure chamber; a carbon dioxide photoresist development chamber; anda photoresist etch chamber.
 18. A system according to claim 17, wherein:said photoresist etch chamber is an ash chamber; said system furthercomprising a carbon dioxide cleaning chamber associated with said ashchamber.
 19. A system according to claim 17, wherein: said photoresistetch chamber is a photoresist strip chamber, said system furthercomprising a carbon dioxide cleaning chamber associated with said stripchamber.
 20. A system according to claim 16, further comprising astorage vessel operatively associated with said controller and each ofsaid carbon dioxide processing chambers.
 21. A system according to claim16, further comprising a second process chemical supply vesseloperatively associated with said controller and at least one of saidcarbon dioxide processing chambers.
 22. A system according to claim 16,further comprising a gas supply vessel operatively associated with saidcontroller and at least one of said carbon dioxide processing chambers.23. A system according to claim 16, wherein said plurality of carbondioxide processing chambers comprises at least three separate processingchambers.
 24. A system according to claim 16, further comprising a bulkcarbon dioxide storage vessel operatively associated with said carbondioxide supply vessel.
 25. A system according to claim 16, furthercomprising: an abatement chemical supply vessel operatively associatedwith said waste collection vessel for adding detoxification orneutralization chemicals to the contents of said waste collectionvessel.
 27. A system according to claim 16, further comprising: apurifier operatively associated with said waste collection vessel forseparating carbon dioxide and waste chemicals.
 28. A system according toclaim 27, further comprising: a return line connecting said purifier tosaid carbon dioxide supply vessel for returning said carbon dioxide fromsaid purifier to said carbon dioxide supply vessel.
 29. A systemaccording to claim 27, further comprising: an abatement chemical supplyvessel operatively associated with said purifier for addingdetoxification or neutralization chemicals to said waste chemicals. 30.A system according to claim 16, further comprising: a clean roomcontaining said plurality of carbon dioxide processing chambers; and acontrol room containing said carbon dioxide supply vessel, said vacuumapparatus, and said first process chemical supply vessel.
 31. A systemaccording to claim 30, said control room further containing saidcontroller and said waste collection vessel.
 32. A system according toclaim 30, further comprising a bulk carbon dioxide storage vesseloperatively associated with said carbon dioxide supply vessel, with saidbulk carbon dioxide storage vessel positioned outside said control room.33. A system according to claim 16, further comprising at least onenon-carbon dioxide processing chamber operatively associated with saidcontroller.
 34. A system according to claim 16, further comprising avacuum pump operatively associated with at least one of said carbondioxide processing chambers and said controller.